mwifiex: correction in mcs index check

mwifiex driver supports 2x2 chips as well. Hence valid mcs values
are 0 to 15. The check for mcs index is corrected in this patch.

For example: if 40MHz is enabled and mcs index is 11, "iw link"
command would show "tx bitrate: 108.0 MBit/s" without this patch.
Now it shows "tx bitrate: 108.0 MBit/s MCS 11 40Mhz" with the patch.

Cc: "3.2.y, 3.3.y, 3.4.y" <stable@vger.kernel.org>
Signed-off-by: NAmitkumar Karwar <akarwar@marvell.com>
Signed-off-by: NBing Zhao <bzhao@marvell.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/cfg80211.c

@@ -634,9 +634,9 @@ mwifiex_dump_station_info(struct mwifiex_private *priv,
 
 	/*
 	 * Bit 0 in tx_htinfo indicates that current Tx rate is 11n rate. Valid
-	 * MCS index values for us are 0 to 7.
+	 * MCS index values for us are 0 to 15.
 	 */
-	if ((priv->tx_htinfo & BIT(0)) && (priv->tx_rate < 8)) {
+	if ((priv->tx_htinfo & BIT(0)) && (priv->tx_rate < 16)) {
 		sinfo->txrate.mcs = priv->tx_rate;
 		sinfo->txrate.flags |= RATE_INFO_FLAGS_MCS;
 		/* 40MHz rate */